Resolves #13835

This finalizes the REM digest-state closeout by writing terminal extraction failures as digestState: 'undigestible' instead of overloading the legacy deferred state, while keeping legacy deferred rows excluded from the steady cadence. findUndigestedSessions() now filters both bounded-out states, so old rows remain compatible and new terminal rows stop re-serving without pretending they were graph-digested.

Evidence: L2 unit/static covered the state-machine ACs; L3 live load-reduction remains post-merge because it requires the orchestrator processing the real REM backlog.

Deltas from ticket

Earlier merged work delivered the extraction terminality and under-band classification pieces. This PR is the final state-machine delta: terminal max-attempt rows become undigestible, legacy deferred remains a supported excluded state, and the tests cover both the candidate filter and max-attempt terminal writes.

Test Evidence

• node --check ai/daemons/orchestrator/services/DreamService.mjs
• node --check test/playwright/unit/ai/daemons/orchestrator/services/DreamService.spec.mjs
• npm run agent-preflight -- ai/daemons/orchestrator/services/DreamService.mjs test/playwright/unit/ai/daemons/orchestrator/services/DreamService.spec.mjs
• npm run test-unit -- test/playwright/unit/ai/daemons/orchestrator/services/DreamService.spec.mjs - 34 passed
• git diff --check
• Pre-push freshness: merge-base HEAD origin/dev == origin/dev; outgoing log contained only fc18b3aeb9 fix(ai): mark terminal REM digests undigestible (#13835)

Post-Merge Validation

• Restart the orchestrator on the merged SHA and confirm bounded-out rows no longer appear in the steady REM candidate set.
• Confirm extraction attempts per cycle drop by the size of the bounded-out pile once the live backlog reaches those rows.

Commit

• fc18b3aeb9 - fix(ai): mark terminal REM digests undigestible (#13835)

Authored by Euclid (GPT-5, Codex Desktop). Session 2cfc471c-c571-4caf-b0c4-77499f43a0ea.